1. Technical Field
The present invention relates to an automatic wake-up device for a radio automatic recognition terminal and a communication method using the terminal. More particularly, the invention relates to an automatic wake-up device for a radio automatic recognition terminal and a communication method using the terminal, in which the radio automatic recognition terminal wakes up in response to various modes of waking up a terminal included in a vehicle in an electronic toll collection system.
2. Related Art
Recently, there has been proposed an electronic toll collection system (ETCS) which reduces the number of men and the time required for collecting tolls on a highway in order to smooth the flow of vehicle traffic.
Typically, an ETCS employs a communication beacon which transmits a radio signal to a communication zone through which a vehicle must pass. The vehicle includes a radio automatic recognition terminal which responds to a polling signal transmitted via the communication beacon as the vehicle passes through the communication zone so that a corresponding toll is automatically collected.
Most vehicle terminals include batteries which operate in a sleep mode at ordinary times, that is, when the vehicle is not near a toll station. The vehicle terminal is awakened when the vehicle approaches the communication beacon and then returns to the sleep mode after communicating with the communication beacon.
Two different wake-up arrangements are utilized in such systems. In a first arrangement, a wake-up beacon is disposed separate from the communication beacon, and the two beacons transmit on different frequencies. Such an arrangement has the disadvantage that, if the vehicle stops at the boundary between the wake-up zone and the communication zone for an extended period of time (such as due to a traffic jam), communication is disabled between the terminal and the beacon, and the vehicle terminal returns to the sleep mode.
A second arrangement does not employ separate beacons, but rather communication data and wake-up data are separately and distinctly encoded and transmitted from the same beacon. However, such an arrangement has the disadvantage that, when vehicles are traveling at high speed and the communication zone is too wide, a large number of vehicle terminals can be in the communication zone at the same time, and this disturbs normal communication.
Therefore, there is a need for the development of an automatic wake-up device for a radio automatic recognition terminal and related communication method that eliminate the problems stated above.